Support these variables in input file

Description

In addition to the question contents, we should support the following elements in the input XML file. For now, we'll preserve the HURIX naming for these (as much as possible), just so the format doesn't change too much. We'll be redefining the format later.

MEDAL - These define the medal cutoffs, in terms of score (time plus penalty time, both of which are measured in milliseconds).

SpeedImpact_Up and SpeedImpact_Down - This is the amount that an arrow push affects the speed. These are expressed in meters/second

MaxTPQ - Maximum time per question. This is the slowest speed supported. This should be interpreted as meters/second. 0 is a possible value.

MinTPQ - Minimum time per question. This is the fastest speed supported. This should be interpreted as meters/second. This time is both the fastest that a player can go by pushing the uparrow key and the speed obtained by turboboost (we can ignore the turboboost parameter)

Note that, in the Hurix implementation, it seems like MaxTPQ is greater than MinTPQ, which doesn't make sense. Let's reuse the variables but in a way that does make sense - MaxTPQ expresses a speed (and a lower speed indicates a larger maximum).

DTPQ - Default time per question. This is the starting speed for the game. It is expressed in meters/second.

DEFAULT_PENALTY - this is the penalty applied for an incorrect answer (in milliseconds). I'm not sure why this is called "default" - there is no way to change it.